Many intracellular processes are carried out or regulated by multi-subunit protein complexes that become active or repressed by the association or dissociation of individual polypeptide subunits.
One such group or family of proteins is related to the .beta. subunit of transducin. Members of this group are all at least somewhat homologous to the .beta.-subunit of transducin at the amino acid level, and contain a varying number of repeats of a particular motif identified in .beta.-transducin. The repeats have been termed ".beta.-transducin", or "WD-40" repeats (Fong, et al.).
Among the members of this protein family (Duronio, et al.) are the G.beta. subunits that couple many receptors to their intracellular effector molecules, G.beta./.gamma. subunits that anchor another protein kinase (the .beta.-adrenergic receptor kinase, .beta.ARK), DNA binding proteins and yeast cell cycle proteins. All of these require a transient protein-protein interaction for their function. However, the sequences at the interface of these proteins and their partners have not been identified.
The following are the references cited above and throughout the specification: